February 13, 2009

The White Sturgeon: A “Living Fossil”

The white sturgeon, ponderous and primeval-looking, is one of the most popular and asked-about animals in the Monterey Bay Habitats exhibit, according to Jim Covel, senior manager of guest experience at the Monterey Bay Aquarium. And no wonder. Sturgeon are the largest freshwater fish in North America. The biggest on record weighed an astounding 1,500 pounds, and they can reach 13 feet or more in length. Sturgeon are sometimes called “living fossils”—they were swimming the world’s waters when dinosaurs roamed the land, and they can live to be over 100 years old. Their every movement seems to imply time on a geologic scale.

The sturgeon has a wizened look that seems to match its movement and demeanor. Four long, downward-pointing whiskers, or “barbels,” are used to troll the ocean floor for clams, shrimps, crabs and mussels, which it scoops up with its extensible mouth. (Aquarium sturgeon are fed krill, chopped fish and squid.) Covel likens the sturgeon’s low slung mouth to a “vacuum cleaner,” as it sucks up its meals. The sturgeon has no scales, but it does have long rows of spiny plates, called “scutes,” plainly visible along its sides. These can offer a surprise to any animal—or person—that happens to bump up against these majestic fish. “You don’t want to wrap your arms around one,” says Covel.

The Fish that Lays the Golden EggsSturgeon are “anadromous,” meaning that they live in salt water, but breed in fresh water. This versatile physiology means that sturgeon are sometimes found in some very unlikely inland habitats. While studying at the University of California, Davis, Covel remembers being summoned to save a sturgeon from the middle of a farmer’s field. The fish ended up there during a flood, and was surprised to find itself “outstanding in its field” once the waters receded. In California, sturgeon are found from the Pacific to the Sacramento Delta.

Sturgeon have traditionally been valued for their roe, popularly known as caviar—a sought-after gourmet delicacy and an occasional status symbol. (Caviar can fetch up to $100 per ounce.) As the fish that lays the golden eggs, sturgeon have come under increasing pressure worldwide. The sturgeon of the Caspian Sea, a traditional source of caviar, are nearing extinction. By 1997, all but two sturgeon species were classified as globally threatened. There are very few commercial fisheries left in the U.S. for sturgeon because of overfishing. The Monterey Bay Aquarium Seafood Watch program recommends U.S. farmed sturgeon as a Best Choice; imported, wild-caught sturgeon are on the Avoid list.

The largest white sturgeon in the Monterey Bay Habitats exhibit comes with its own rich history. It was a mere 24 inches long when first acquired by San Francisco’s Steinhart Aquarium in 1990. It was donated to the Monterey Bay Aquarium in 2006 when the Steinhart underwent renovations. This giant fish is now estimated to be 26 years old, more than six feet long and over 70 pounds!